It does not break the link in your transaction history, because your sending address and your receiving address are the part of a single coinjoin transaction. The link albeit obfuscated will exist forever because blockchain is immutable and transparent. Under certain circumstances the connnection between two addresses can be found out with a high degree of accuracy. In order to really break the link and obfuscate the history of transactions, you should use third party mixing services or P2P deals with physical cash.

It does not completely do it, nor does it permanently do so. As the ledger is public and immutable, if a way is ever found to link joined coins, your entire past of CoinJoins will be connected as well.

Think of CoinJoin like a room nobody has the key to, besides you. You can hide whatever you like in there, but if anyone ever finds the way to open it, they'll know all your secrets. All you have to do is be extra cautious after mixing/joining/whirlpooling coins. If you're using them the wrong way (like linking joined coins to non-joined ones you own, sending the coins to previously used addresses or exchanges etc), going through these privacy-improving procedures is in vain.

Thank you, there's a lot of good information here I did not consider!

I wouldn’t say that it completely severs any connection you have on a certain transaction as it’s still there, though it does its job pretty well considering that people haven’t complained about it not doing what it’s supposed to do after a long time of existing. Personally I think what you do afterwards is what may give away information to the likes of Chainalysis. These guys have a trick or two up their sleeves that may get you without you even knowing it. As what o_e_l_e_o put it, using block explorers almost immediatey to check your transactions might give away some info. It’s worth noting that block explorers can see who connected from where, and what they viewed from the explorer, so I’d better use something to mask my IP whilst looking on a few, unrelated transactions first before moving in on that particular transaction I would really like to view in which coinjoin is used just to obfuscate the trail.

If its going to be traced then this is going to be traced then its a risk for users too? I happen to watch this video today and it looks like they are trying to make it a crime to mix up coins.

What do you think about this DOJ crypto framework being reviewed by Coin Bureau about mixing?  Time 11:38  https://www.youtube.com/watch?v=r-ksQLS6uQM 

It's a near meaningless term. Lets say I have some bitcoin which some centralized exchange somewhere has deemed is "tainted". I coinjoin that bitcoin with 49 other inputs. Are all 50 outputs tainted? One of those outputs is now deposited to a big exchange and consolidated in to their hot wallet. Is every withdrawal from that exchange now tainted? Given enough time, every bitcoin in active circulation will be "tainted" in one way or another because it has been combined/consolidated with some other bitcoin.

Further, how far back do we go? Bitcoin which was hacked and moved in one transaction to another wallet. Tainted? Sure. What about once that bitcoin has gone through 20 more transactions, been split up multiple times, and is now owned by someone else. Still tainted? Maybe. What about after 100 transactions? What about after 1,000? What about bitcoin which were "tainted" in 2015. Are they still tainted? If not, why not? When did they become clean again?

Tainted bitcoin is a completely arbitrary and near meaningless distinction, made by centralized exchanges as a way to control their customers and steal funds.

It does as long as most people you mixed with don't do anything to compromise the privacy you have gained. A lot of the coins involved in the PlusToken scam were able to be tracked. They thought that simply running their coins through Wasabi would be enough so they forked the wallet to allow them to keep reusing the same addresses and did some other dumb things to break their own privacy.